Add support for running commands on key press (#566)

Based on option `command` in key binding section in config, e.g.

    - { key: N,        mods: Control|Shift,    command: alacritty }
    # or
    - {
        key: N,
        mods: Control|Shift,
        command: {
          program: "alacritty",
          args: ["-e", "vttest"],
    }}

specified command will be run in the background on key press. Alacritty
doesn't wait for its result nor block IO.

src/config.rs

@@ -378,6 +378,17 @@ impl de::Deserialize for ActionWrapper {
     }
 }
 
+#[derive(Debug, Deserialize)]
+#[serde(untagged)]
+enum CommandWrapper {
+    Just(String),
+    WithArgs {
+        program: String,
+        #[serde(default)]
+        args: Vec<String>,
+    },
+}
+
 use ::term::{mode, TermMode};
 
 struct ModeWrapper {
@@ -517,7 +528,8 @@ impl de::Deserialize for RawBinding {
             Mode,
             Action,
             Chars,
-            Mouse
+            Mouse,
+            Command,
         }
 
         impl de::Deserialize for Field {
@@ -527,7 +539,7 @@ impl de::Deserialize for RawBinding {
                 struct FieldVisitor;
 
                 static FIELDS: &'static [&'static str] = &[
-                        "key", "mods", "mode", "action", "chars", "mouse"
+                        "key", "mods", "mode", "action", "chars", "mouse", "command",
                 ];
 
                 impl Visitor for FieldVisitor {
@@ -547,6 +559,7 @@ impl de::Deserialize for RawBinding {
                             "action" => Ok(Field::Action),
                             "chars" => Ok(Field::Chars),
                             "mouse" => Ok(Field::Mouse),
+                            "command" => Ok(Field::Command),
                             _ => Err(E::unknown_field(value, FIELDS)),
                         }
                     }
@@ -577,6 +590,7 @@ impl de::Deserialize for RawBinding {
                 let mut mode: Option<TermMode> = None;
                 let mut not_mode: Option<TermMode> = None;
                 let mut mouse: Option<::glutin::MouseButton> = None;
+                let mut command: Option<CommandWrapper> = None;
 
                 use ::serde::de::Error;
 
@@ -626,17 +640,32 @@ impl de::Deserialize for RawBinding {
                             }
 
                             mouse = Some(visitor.visit_value::<MouseButton>()?.into_inner());
-                        }
+                        },
+                        Field::Command => {
+                            if command.is_some() {
+                                return Err(<V::Error as Error>::duplicate_field("command"));
+                            }
+
+                            command = Some(visitor.visit_value::<CommandWrapper>()?);
+                        },
                     }
                 }
 
-                let action = match (action, chars) {
-                    (Some(_), Some(_)) => {
-                        return Err(V::Error::custom("must specify only chars or action"));
+                let action = match (action, chars, command) {
+                    (Some(action), None, None) => action,
+                    (None, Some(chars), None) => Action::Esc(chars),
+                    (None, None, Some(cmd)) => {
+                        match cmd {
+                            CommandWrapper::Just(program) => {
+                                Action::Command(program, vec![])
+                            },
+                            CommandWrapper::WithArgs { program, args } => {
+                                Action::Command(program, args)
+                            },
+                        }
                     },
-                    (Some(action), _) => action,
-                    (_, Some(chars)) => Action::Esc(chars),
-                    _ => return Err(V::Error::custom("must specify chars or action"))
+                    (None, None, None) => return Err(V::Error::custom("must specify chars, action or command")),
+                    _ => return Err(V::Error::custom("must specify only chars, action or command")),
                 };
 
                 let mode = mode.unwrap_or_else(TermMode::empty);
@@ -659,7 +688,7 @@ impl de::Deserialize for RawBinding {
         }
 
         const FIELDS: &'static [&'static str] = &[
-            "key", "mods", "mode", "action", "chars", "mouse"
+            "key", "mods", "mode", "action", "chars", "mouse", "command",
         ];
 
         deserializer.deserialize_struct("RawBinding", FIELDS, RawBindingVisitor)

src/input.rs

@@ -20,6 +20,7 @@
 //! determine what to do when a non-modifier key is pressed.
 use std::borrow::Cow;
 use std::mem;
+use std::process::Command;
 use std::time::Instant;
 
 use copypasta::{Clipboard, Load, Buffer};
@@ -144,6 +145,9 @@ pub enum Action {
     /// Paste contents of selection buffer
     PasteSelection,
 
+    /// Run given command
+    Command(String, Vec<String>),
+
     /// Quits Alacritty.
     Quit,
 }
@@ -174,6 +178,17 @@ impl Action {
                         warn!("Error loading data from clipboard. {}", Red(err));
                     });
             },
+            Action::Command(ref program, ref args) => {
+                trace!("running command: {} {:?}", program, args);
+                match Command::new(program).args(args).spawn() {
+                    Ok(child) => {
+                        debug!("spawned new proc with pid: {}", child.id());
+                    },
+                    Err(err) => {
+                        warn!("couldn't run command: {}", err);
+                    },
+                }
+            },
             Action::Quit => {
                 // FIXME should do a more graceful shutdown
                 ::std::process::exit(0);